As my 1997 vintage Lunor spectacles – having single vision lenses – were lost and stamped into the soil of the garden in May 2015, they were found by following intuitive directions from my brother two months later, now with a broken frame, but with its mineral glasses intact.
I already wrote a blog about those spectacles, in Norwegian language.
Luckily, this model, a copy of an 1830 vintage style, is still available in a local shop several hundred years later; namely in SHOC Lifestyle downtown Oslo. And so, after ten years with a gold plated frame, time had come to make a change to a silver plated alternative. A great, timeless frame now again on the tip of the nose, and all is well, then?
My current spectacles
But as it were, the lost spectacles had started a process related to a further need for presbyopia correction. The current glasses are a compromise as they are sufficiently farsighted for car driving, but not perfect for that, while at the same time serving as computer near field glasses at +60 cm. A good job done by the Brilleland shop a few years ago as my presbyopia transition ebbed then. On a good day, these lenses works fine as I am most often standing while working with the laptop on a grand piano (resulting in +60 cm distance to computer), but when my eyes are not yet “awake” or tired, or if I am doing detailed on-screen Photoshop work at distances down to 45 cm, I have been using a homemade “snapon??? solution that corrects +1. With this solution I can count onscreen pixels with ease, while simultaneously acting out a secret urge as “the mad professor”. In other words, it doesn’t look to good, but it works for me and could be categorized as a kind of “bifocal” variant with the computer screen as prime target. I sometimes forget to take of the +1 when walking around as well.
My main question and need
The question was if it would be possible to replace this home brew solution with latest technology progressive lenses; inter alias to replace the Lunors with one pair of glasses that via progression could also take care of the home made +1 additive presbyopia correction? As it seems, the answer is unfortunately still no, or at least, it is not yet yes, and here comes the highlights of my experiences:
New progressive glasses
I ordered a new pair of progressive glasses from Carl Zeiss, but by misunderstanding, these lenses had a near field zone suited for a reading distance down to 30 cm, this near field therefore (at first glance) being in too large “contrast??? to the distance zone of the lenses. Thus, these lenses were replaced with a set from Rodenstock, being tuned in its near field zone to “computer???; approx minimum 45 cm. Note that this is not an article about Zeiss vs. Rodenstock, that was coincidental, and both suppliers seem to offer comparable lenses technologies.
The Optician’s faulty warning
In literally all shops and websites focusing on progressive lenses, I have been met with the upfront warning that there exists minimum lens height, below which a progressive lens may become unsatisfactory due to too dynamic (compressed) transition on the vertical axis, between the near zone and distance zone. My current Lunors (above) has frequently been pointed to as an example of an unsuitable frame in this regard. The only shop not giving this warning, but on the contrary stating that any “normal??? frame will normally work well with progressive lenses, is Shoc Lifestyle, and they are right in my case: As long as I am operating round and about, progressive lenses are clearly one step up in perceived optical quality, compared to the lenses in my old Lunors as described above. While the Rodenstock variant is less provocative for obvious reasons, both these and the Carl Zeiss alternative works better than the Lunors. The progressive lenses results in various optical distortions and artefacts, yes indeed, but after a couple of minutes only, my eyes started to enjoy its sharper sight on the medium to long distances. The claimed problem with difficult accustomisation to the transition along the vertical axis is simply not true in my case. I suspect most people will say the same; the vertical axis on medium to long distances is not a problem, but a great solution. Opticians warn that it may take weeks to adapt, but in reality it is a five minute job. It is all a matter of attitude, one need to be prepared to accept that the comprise involves optical distortion, causing to a certain degree e.g. head-movement instead of eye-movement in order to relocate the “sweetspot??? of the lenses for any given distance.
The lateral axis is the problem
I have no other reference but my own particular case, but let me tell and show that there is another major problem with progressive lenses that neither the opticians nor the lenses technology suppliers are mentioning, at least not in a way that caused my alarm bells to ring. The problem with progressive lenses is a “violent” astigmatism along the lateral axis in the near field zone. For example, on the Carl Zeiss website, all that is stated is this:
“All progressive addition lenses are more concave in the bottom portion. … As a result of the manufacturing process, the edges of this area are out of focus – and the severity of this differs depending on the quality of the progressive addition lens design and the level of customisation. … It is the specific design parameters that make ZEISS progressive lenses so unique minimise these distortions and allow the user to enjoy comfortable vision throughout.”Carl Zeiss goes on to describe the difference between ordinary and individually customized lenses, like e.g. these two variants; standard and individual, just observe that the individual variant has much smaller areas of distortion.
New spectacles with progressive lenses
If I had received the individually customized lenses illustrated above (right) from either Carl Zeiss (attempt 1) or Rodenstock (attempt 2), I am quite certain that I would have been fairly happy as the so-called distorted areas are so small that they can be ignored in practical life. However, this is not my case. The strange thing is that even if I got the most costly variant (at least from RodenStock); namely the mineral glass variant of the so called “Impressive 1.6” type, both lenses variants are worse than the “standard” variant illustrated above. The Carl Zeiss alternative is equally lousy in this regard.
The distortion is astigmatism
And what is trivialized as “distortion” on the Carl Zeiss website, is actually severe astigmatism. Using Photoshop I have created a quite accurate illustration of how a computer screen looks through my “newest technology” progressive lenses. I am sorry, I am not pedantic, but these lenses just don’t do the job, and the most severe error is not the astigmatism. The main problem is that, due to the significant differences along the lateral axis of the near field, there is a lot of skewed and bent views as the head (not the eyes) are moved. (The distance field is perfect in this regard and outside scope of this discussion). I have these conclusions:
- Eye movement
Eye movement results in perceived astigmatism along the lateral axis, to the extent that – in my example below – most of the center column is readable and clear, while the leftmost and rightmost part of the two other columns are literally unreadable. Head movement is therefore the only option, but that is very funny thing to do when you read a screen or a book.
- Head movement
Head movement results in severely skewed views. The screen (below) is jumping hither and dither with no angles at 90 degrees. To a certain extent, I could perhaps accept this if there were no or minimal astigmatism, but these two combined errors creates a true mess.
Technical reasons missing
Searching everywhere, I have been unable to find any kind of description of the technical reasons for these type of (seemingly) standard errors in progressive lenses. The explanation is hidden in statements like the quote above from Carl Zeiss, pointing to “the production process”.
Here is therefore a few speculations as to the actual cause of the astigmatism that seems to come with progressive lenses.
- An error in my particular case
Hopefully, I have been subject to a standard production from both suppliers, and then perhaps my natal astigmatism or other eyesight “data” by unlucky break is too much to handle within the context of a “standard progressive lens”? If I understand the production process correctly, the normal case is to base the lenses production on semi-finished lenses, perhaps imposing certain limitations?
- Technological incapacity
Could it simply be that the technological advancements in the field of progressive lenses has been subject to almost a standstill the latest decade, because this blog could have been written at least a decade ago. Perhaps it is still literally impossible to produce “the perfect” progressive lenses, even if a thousand dollars were offered?
The cost of producing progressive lenses properly attuned to individual needs is simply too high, e.g. causing Carl Zeiss to define a particular offer for those who can pay; “Glasses for leaders“?
- Cosmetic reasons
Studying the websites of Carl Zeiss and Rodenstock, it becomes clear that both these suppliers have put over-emphasize on cosmetics, “lifestyle” and fashion trends. At the same time, it is literally impossible to find technological white papers explaining the technology and its constraints.
Perhaps the reasons for the astigmatic effects in progressive lenses is that priority is put on fashion and looks, rather than eyesight perfectness? Reading about progressive lenses, there is indeed a lot of focus on various “prism thinning” techniques, etc, obviously resulting in more decent looks and a more lightweight spectacle, but to ask rhetorically:
Would I accept thicker lenses if that would grant a better optical result than illustrated in this blog? Answer is: Yes. Indeed!
What I want
I would like to have a commercialized, progressive lenses that are smooth in its vertical transitions, but that are single vision, or close to it, in any lateral axis. As stated above, a little imperfectness I could live with, but if possible, I would like a “bifocal” with smooth and mostly invisible vertical transitions between far and near areas of the lenses.
Is this really technical impossibility? That would be hard to believe.
Actually, if I put the progressive lenses on top of my original Lunors in another home-made sandwich, most of the “outer” astigmatism of the near field is gone. It could be be complete coincidence, but it happened.
Via a little experimentation, I can myself produce “bifocal” progressive lenses in several ways. Carl Zeiss should be able to do the same.